Arrangement for igniting and a supplying gas and/or vapour discharge lamp

ABSTRACT

The invention relates to igniting and supplying a gas- and/or vapour discharge lamp. According to the invention a second voltage source is used in addition to the common voltage source, which second source ensures both the ignition of the lamp and the maintenance of a current flowing through the lamp when the first voltage source has failed due to interference.

United States Patent Moerkens et a1.

ARRANGEMENT FOR ICNITING AND A SUPPLYING GAS AND/0R VAPOUR DISCHARGE LAMP Jozef Cornelis Moerkens; Giovanni Porro, both of Emmasingel, 'Eindhoven, Netherlands U.S. Philips Corporation, New York, NY. Apr. 8, 1970 inventors:

Assignee:

Filed:

Appl. No.:

Foreign Application Priority Data Apr. 12, 1969 Netherlands ..6905676 U.S. Cl ..315/86 Int. Cl. ..H05b 37/00 Field oiSearch ..315/86,87,88, 127, 171,360,

315/D1G. 5, DIG. 7; 307/64, 66

us] 3,657,597 1451 Apr. 18, 1972 References Cited FORElGN PATENTS OR APPLICATIONS Primary ExaminerNathan Kaufman Attorney-Frank R. Trifari [5 7] ABSTRACT The invention relates to igniting and supplying a gasand/or vapour discharge lamp. I

According to the invention a-second voltage source is used in addition to the common voltage source, which second source ensures both the ignition of the lamp and the maintenance of a current flowing through the lamp when the first voltage source has failed due to interference.

10 Claims, 1 Drawing Figure l 1 17 l 20 iv -22 I i i ['T 7 10 I :1 '1 is l 11 i 12 T9 1s 8/1967 Great Britain ..307/64 PVAIENTEDAPR 181972 INVENTOR6. JOZEF C.MOERKEN$ GIOVANNI PORRO AGENT.

ARRANGEMENT FOR IGNITING AND A SUPPLYING GAS AND/R VAPOUR DISCHARGE LAMP Thisinvention relates to an arrangement for igniting and supplying a gas and/or vapour discharge lamp provided with at least two electrodes, which arrangement is intended to be connected to two voltage sources, the lamp mainly receiving current from one of these voltage sources, i.e., the first voltage source.

An arrangement of the kind described in the preamble is known, for example, from the Netherlands Pat. application No. 6,408,592. A drawback of this known arrangement is that the lamp receives current from the two voltage sources during the operating condition. Both voltage sources must therefore have a capacity such that this permanent supply is possible. This is a drawback.

An object of the invention is to obviate or at least to mitigate this drawback. I

-An arrangement will be described for igniting and supplying a gas and/or vapour discharge lamp provided with atleast two electrodes, which arrangement is intended to be connected to two voltage sources, the lamp mainly receiving current from one of these voltage sources, i.e., the first voltage source. The arrangement is characterized in that only in the switchedon condition of the second voltage source will the voltage across the lamp electrode, in the -case of a lamp not yet ignited, be higher than the cold ignition voltage of said lamp,and that means are provided which cause the second voltage source to take over the supply of the lamp when the voltage of the first voltage source fails due to interference.

An advantage of this arrangement is that the second voltage source need only have a limited capacity. A further advantage is that the second voltage source can perform a dual function, i.e. in the first place to help the lamp ignite and in the second place to take over the supply of current to the lamp when the first voltage source has failed due to interference.

It is known per se that a lamp can be connected to two different voltage sources wherein the supply of the lamp is taken over by the second voltage source when the first voltage source fails due to interference (see, for example-US Pat. No. 2,593,952), but in this known arrangement there are no means to ignite the lamp in the cold condition with the aid of this second voltage source.

Cold ignition voltage is understood to mean the ignitio voltage of the lamp in its cold condition. Generally the hot ignition voltage of a lamp is understood to mean the ignition voltage of the lamp in its hot condition.

An arrangement according to the invention may be used, for example, for the illumination of sports events, for example, football fields. When illuminating a sporting event it is of paramount importance that even when the supply voltage drops out for a very short time, for example, a few periods, the supply arrangement causes the lamps to ignite as soon as the supply voltage is available again. If no special steps have been taken and when, for example, high-pressure mercury vapour discharge lamps provided with metal halides are used, it will be necessary to wait (even in thecase of a short interference of the power supply) for a rather long period, for example, minutes before these lamps have sufficiently cooled off to be reignited again. Such a long period is inadmissible, for football games or the like. This is certainly the case when such a game is televised.

The present invention provides a solution in that the second voltage source insures both the first ignition of the lamp and maintains a given lamp .current after the first voltage source has failed. if a short period later the supply voltage, that is to say, the first voltage is available again, the lamp can directly be reignited. The football ground then need not be in a minute's darkness.

It is feasible that the circuit of thesecond voltage source is connected, for example, to a photosensitive element which reacts to the light from the discharge lamp. This may be effected in such a manner that when the discharge lamp is extinguished this, photosensitive element connects the second voltage source to the lamp.

In an advantageous embodiment of an arrangement according to the invention the connection from a connecting terminal for connecting the first voltage source to the lamp includes a circuit element which comprises an energizing winding of a relay or is magnetically coupled thereto, the contact of this relay being provided in the connection from a connecting terminal of the second voltage source to the lamp such that the contact opens when a current flows through the energizing winding.

An advantage of this preferred embodiment is that it is then very simple for the second voltage source to take over the lamp supply when the first voltage source has failed due to interference.

It is feasible that both the first voltage source and the second voltage source are alternating voltage sources. The first alternating voltage source may consist of. an ordinary supply voltage of, for example, 220 Volt 50 Hz. The second voltage source is then formed, for example, by an alternating current aggregate which is switched on at the beginning of a game. This alternating current aggregate may alternatively serve, for example, for illuminating emergency exit signs,etc.

In an arrangement according to the invention the first voltage source is preferably an alternating voltage source and the second voltage source is a direct voltage source with a DC-AC converter whose AC-frequency is more than 1,000 Hz being included between the terminals of the direct voltage source and the lamp.

An advantage of this preferred arrangement is that a direct voltage source is used which, as is known, is always ready to be put into operation. The combination with the DC-AC converter provides a supply with no unwanted DC-component oc- This means that the lamp still has substantially the same luminance after the current has been taken over. lt is likewise feasible that after the supply of the first voltage source has failed, the second voltage source is only effective to maintain a certain ionisation in the discharge tub of the lamp.

The second source may be switched on, for example, even before the first voltage source is put into operation.

In a preferred arrangement according to the invention the connection from the connecting terminals of the first voltage source to the lamp includes a switch which is coupled to a switch provided in the connection from the connecting terminals of the second voltage source to the lamp. The two switches are coupled in such a manner that one switch is in the open (closed) condition when the other switch is likewise in the open and closed condition, respectively.

An advantage of this preferred arrangement is that the second voltage source is then always operating simultaneously with the first voltage source.

It is feasible that after the occurrence of a failure in the first voltage source, the second voltage source continues to feed the lamp for a very long period. v

In an advantageous embodiment of an arrangement according to the invention the connection from a connecting terminal of the second voltage source to the lamp includes a contact (second contact) of a relay which is connected to an auxiliaryarrangement likewise intended to be supplied from the second voltage source. This auxiliary arrangement energizes the last-mentioned relay so that the second contact opens some time, e.g., an operating period, after the instant when the is that the second voltage source is switched off some time I after the occurrence of a failure, for example, aquarter of a minute later. A complete exhaustion of the second voltage source is then avoided. Such an exhaustion would be particuwould then have to remain operative permanently, namely until the lamp has sufiiciently cooled off to be able to reignite. Under certain circumstances this may involve an unwanted exhaustion of the second voltage source.

in a further'advantageous arrangement according to the invention, wherein the voltages applied to the lamp are lower than the hot ignition voltage of the lamp, the auxiliary arrangement is provided with a test section which is activated when the voltage of the first voltage source is available again after an interruption and after the operating period sub sequent to the instant of putting the second voltage source into operation has elapsed, said test section connecting the second voltage source only intermittently to the lamp when the lamp does not receive current from the second voltage source.

An advantage of the last-mentioned preferred arrangement is that the second voltage source need not be unduly exhausted (for example, due to a current flow through the inductor 3 in the drawing) when the lamp is still in its hot extinguished condition. In fact, the situation is such that after the so-called operating period has elapsed the test arrangement first checks whether the voltage of the second voltage source is-already sufficient to ignite the lamp. if this is not the case the second voltage source is switched off again and the test arrangement checks sometime thereafter to determine whether the lamp is ready to be ignited. This operation is repeated until the available voltage once again exceeds the ignition voltage of the lamp. The lamp then ignites. Subsequently the first voltage source takes over the current supply to the lamp.

in order that the invention may be readily carried into effect, an embodiment thereof will now be described in detail,

- by way of example, with reference to the sole FIGURE of the accompanying diagrammatic drawing.

In this drawing the reference numerals 1 and 2 denote connecting terminals adapted for connection to an alternating voltage source of, for example, 220 V, 50 Hz. Terminal 1 is connected to a ballast inductor 3. The other end of this inductor is connected to an electrode of a high-pressure-mercury vapour discharge lamp 4. This is a discharge tube which comprises metal halides. The other electrode of the lamp is connected through an energizing winding 5 of a relay to a switch 6. The other end of the switch 6 is connected to the connecting terminal 2.

The reference numerals 7 and 8 denote connecting ter- I minals to which a direct voltage source 9 is connected. The terminal 7 is connected through a switch 10 to a relay contact 11 and through a switch 12 to a DC-AC converter 13. The terminal 8 of the direct voltage source 9 is likewise connected to the con verter 13 through a different line 14. The electrodes of the lamp 4 are also connected to the converter 13, namely through a conductor 15 and a conductor 16, the latter includ-- ing a capacitor 17. The switch 10 is mechanically coupled to the switch 6. The relay contact of 11 is the contact the relay energizing winding 5. The Figure furthermore shows an auxiliary arrangement 18 which is connected between the connection from the relay contact 11 and a relay contact 12 on the one hand and to the connection wire 14 on the other hand. This auxiliary arrangement includes a time switch having a contact 12. The switch 12 is bridged by a circuit which comprises a contact 19. The contact 19 may be closed by means of a rotatable cam disc 20. This cam disc is driven, by an electric motor 21. s

The electric motor 21 is connected at one end to the terminal 1 and the inductor 3 andat the other end through a switch 22 to the junction between the energizing winding 5 with short lapses and current is supplied to the converter 13.

. connected to terminals 1 and 2 and a direct voltage source 9 is connected to terminals 7 and 8. When the switches 6 and 10 are closed, the supply of the alternating voltage source to terminals 1 and 2 will produce a voltage across the electrodes of the lamp 4. This voltage is, however, insufficient to ignite the lamp 4. However, since the switch 10 also is closed and the contacts 11 and 12 are closed in the rest position, the converter 13 is energized from the direct voltage source 9. This converter then likewise applies a voltage across the electrodes of the lamp 4 through the connection wires 15 and'16. This is a voltage of high frequency having a rather high peak value.

' ductor 3, the lamp 4, the energizing winding 5 and the switch 6. Due to this current flow the relay 5 is energized and the contact 11 is opened. As a result the voltage supply to the converter 13 is discontinued. In this situation the lamp 4 is normally energized from the alternating voltage source connected to the terminals 1 and 2. In this case no current is derived anymore from the direct voltage source 9.

The following will happen if during this situation, when the lamp operates an interruption occurs for a very short time, for, example, a few periods of the alternating voltage. The lamp current flowing through the enerzing winding 5 is interrupted and as a result the contact 11 is closed again. The converter 13 is consequently put into operation again and a peak voltage is applied across the lamp electrodes again. The converter 13 is put into operation with such a small delay that the ionisation present in the lamp can be maintained. in the example described the current which is supplied to the lamp 4 by the converter 13. becomes considerably smaller than the normal lamp operating current, for example, only about 5 percent of the current which is nonnally supplied by the alternating voltage source from terminals 1, 2 to the lamp 4. If after a short time, for example, a few periods, the alternating voltage at terminals 1, 2 has returned again, the lamp 4 will directly reignite. This is so because the ionisation has been maintained in the contact 12 the direct voltage source is switched off 15 seconds after the alternating voltage across the terminals 1, 2

has dropped out. If the alternating voltage across terminals 1,

2 returns 15 seconds after the occurrence of the interference, the following happens. The motor 21 is started through switch 22. This motor activates the cam disc 20. The disc 20 intermittently closes the contact, 19 so that the switch 12 is shunted This means that voltage peaks are applied to the lamp 4 for short periods. When initially the lamp is still in its hot condition, these voltage peaks will be insufficient to reignite this.

lamp. However, as this lamp cools off further, the lamp wiil ignite as soon as the available voltage is sufficiently high.

When the lamp is ignited, the AC supply from terminals 1, 2 will take over the entire supply of the lamp 4 so that a current starts to flow again through the inductor 3, the energizing winding 5 and the switch 6. The contact 11 will then be reopened and the direct voltage source will be put out of operation. Opening of the switch 11 also means that the time switch 18 returns to-its zero position again. This time switch is then ready again for the next procedure. 5

It is evident that scanning with the aid of the cam disc 20 takes place only once when, for example, the alternating voltage across the tenninals 1, 2 has been absent for a very long procedure is actually the same as that initially referred to. In-

fact, the lamp 4 is first ignited with the of the direct voltage source and the supply of the lamp is then taken over by the altemating voltage source at the terminals 1, 2. In a certain embodiment the lamp 4 was a lamp of 2,000 Watts. The inductor 3 had a value of 003 Henry and the converter provided 900 Volts at 8,000 Hz. Capacitor 17 had a capacitance of 7 kp- F arad. The cold ignition voltage of the lamp 4 is approximately 600 Volts, and the hot ignition voltage is more than 10,000 Volts.

As already noted hereinbefore the arrangement described is particularly suitable to beused for the illumination of sports grounds. This certainly applies when television recordings are made. However, it is alternatively possible for the arrange ment to be used for other illumination projects where it is likewise important that long interruptions do not occur. The time switches and the test arrangements described may of course also be replaced by arrangements which have a different construction and which are equipped, for example, with controlled semiconductor elements.

ln the relevant case the direct voltage source is used both as an ignition arrangement for the lamp 4 and as the supplier of a lamp current in emergency cases, that is to say, when the voltage across the terminals 1 and 2 has dropped out.

What is claimed is:

1. An ignition supply circuit for an electric discharge lamp of the type exhibiting a predetermined cold ignition voltage comprising, a first source of voltage of a value below the lamp cold ignition voltage, means for coupling said first voltage source across the lamp electrodes for supplying the operating current thereto during normal operation of the lamp, a second 1 source of voltage of a value above the lamp cold ignition voltage, switching means for coupling the second voltage source across the lamp electrodes to ignite the lamp, means for sensing the condition of the lamp to cause said switching means to disconnect the second voltage source from the lamp when the lamp draws current from the first voltage source and to reconnect the second voltage source to the lamp in the event the lamp is deenergized due to a failure of the first voltage source thereby to supply an uninterrupted current to the lamp from said second voltage source for a given period of time subsequent to the failure of the first voltage source.

2. A circuit as claimed in claim 1 wherein the first voltage a terminal of the second voltage source and a lamp electrode and coupled to said first switch so that said switches open and close together in synchronism.

5. A circuit as claimed in claim 1 wherein said switching means includes a normally closed switch contact connected between a terminal of the second voltage source and a lamp electrode, a timing device connected acrosssaid second voltage source for controlling the operation of said switch contact so as to open same at a given time after the second voltage source is applied to the lamp, said given time being greater than the normal ignition time for the lamp.

6. A circuit as claimed in claim 5 wherein the lamp further exhibits a predetennined hot ignition voltage of a value such that the voltages applied to the lamp from said first and second voltage sources are lower than said hot ignition voltage of the lamp, said timing device further comprising a test section which is activated when the voltage of the first voltage source is once again available after a failure thereof and upon the operation of said switch contact which occurs after the lapse of said given time, said test section including means for inter-' mittently connecting the second voltage source to the lamp to maintain the flow of normal lamp operating current subsource comprises an alternating voltage source and the second voltage source comprises a direct voltage source and a DC-AC converter supplying an alternating current frequency of 1,000 lb or more and connected between the terminals of the direct voltage source and the lamp electrodes.

3. A circuit as claimed in claim 1 wherein said sensing means is included in said coupling means and comprises a relay winding responsive to the supply current from said first voltage source, said relay having a normally closed contact in a lead provided between one terminal of the second voltage source and a lamp electrode whereby the contact is opened when a given current flows through the relay winding.

4. A circuit as claimed in claim 1 wherein said coupling means includes a first switch connected between a terminal of the first voltage source and a lamp electrode and said switching means includes a second switch connected between sequent to ignition, a second source of high frequency-AC voltage of a value above the lamp ignition voltage, switching means for simultaneously connecting said first and second voltage sources across the lamp electrodes whereby the lamp is ignited by said second voltage source whereupon the first voltage source supplies the normal operating current to said lamp, second switching means responsive to the lamp current supplied by said first voltage 'source for opening the circuit between the second voltage source and the lamp when said current fiows and to close the circuit between the second voltage source and the lamp when said current drops below a given value sufficient to maintain the flow of lamp current, whereby the second voltage source supplies a reduced operating current to said lamp.

9. A circuit as claimed in claim 8 wherein said second volting device connected across the terminals of said DC voltage source via said switching contact and having a normally closed contact connected in series with a terminal of the DC voltage source and an input terminal of the converter whereby activation of said timing device after a given time period opens said v normally closed contact to deenergize the converter. 

1. An ignition supply circuit for an electric discharge lamp of the type exhibiting a predetermined cold ignition voltage comprising, a first source of voltage of a value below the lamp cold ignition voltage, means for coupling said first voltage source across the lamp electrodes for supplying the operating current thereto during normal operation of the lamp, a second source of voltage of a value above the lamp cold ignition voltage, switching means for coupling the second voltage source across the lamp electrodes to ignite the lamp, means for sensing the condition of the lamp to cause said switching means to disconnect the second voltage source from the lamp when the lamp draws current from the first voltage source and to reconnect the second voltage source to the lamp in the event the lamp is deenergized due to a failure of the first voltage source thereby to supply an uninterrupted current to the lamp from said second voltage source for a given period of time subsequent to the failure of the first voltage source.
 2. A circuit as claimed in claim 1 wherein the first voltage source comprises an alternating voltage source and the second voltage source comprises a direct voltage source and a DC-AC converter supplying an alternating current frequency of 1,000 Hz or more and connected between the terminals of the direct voltage source and the lamp electrodes.
 3. A circuit as claimed in claim 1 wherein said sensing means is included in said coupling means and comprises a relay winding responsive to the supply current from said first voltage source, said relay having a normally closed contact in a lead provided between one terminal of the second voltage source and a lamp electrode whereby the contact is opened when a given current flows through the relay winding.
 4. A circuit as claimed in claim 1 wherein said coupling means includes a first switch connected between a terminal of the first voltage source and a lamp electrode and said switching means includes a second switch connected between a terminal of the second voltage source and a lamp electrode and coupled to said first switch so that said switches open and close together in synchronism.
 5. A circuit as claimed in claim 1 wherein said switching means includes a normally closed switch contact connected between a terminal of the second voltage source and a lamp electrode, a timing device connected across said second voltage source for controlling the operation of said switch contact so as to open same at a given time after the second voltage source is applied to the lamp, said given time being greater than the normal ignition time for the lamp.
 6. A circuit as claimed in claim 5 wherein the lamp further exhibits a predetermined hot ignition voltage of a value such that the voltages applied to the lamp from said first and second voltage sources are lower than said hot ignition voltage of the lamp, said timing device further comprising a test section which is activated when the voltage of the first voltage source is once again available after a failure thereof and upon the operation of said switch contact which occurs after the lapse of said given time, said test section including means for intermittently connecting the second voltage source to the lamp during the time said switch contact is open.
 7. A circuit as claimed in claim 1 wherein said sensing means is arranged in the supply circuit so as to respond to the lamp current supplied by said first voltage source and so as to be substantially non-responsive to the lamp current supplied by said second voltage source.
 8. An ignition supply circuit for an electric discharge lamp comprising, a first source of low frequency AC voltage of a value below the lamp ignition voltage but of a value sufficient to maintain the flow of normal lamp operating current subsequent to ignition, a second source of high frequency AC voltage of a value above the lamp ignition voltage, switching means for simultaneously connecting said first and second voltage sources across the lamp electrodes whereby the lamp is ignited by said second voltage source whereupon the first voltage source supplies the normal operating current to said lamp, second switching means responsive to the lamp current supplied by said first voltage source for opening the circuit between tHe second voltage source and the lamp when said current flows and to close the circuit between the second voltage source and the lamp when said current drops below a given value sufficient to maintain the flow of lamp current, whereby the second voltage source supplies a reduced operating current to said lamp.
 9. A circuit as claimed in claim 8 wherein said second voltage source comprises a source of DC voltage coupled to the input of a DC-AC converter via a part of said switching means and the output of said converter is directly connected across the lamp electrodes, and said second switching means comprises a current sensing element in series with said first voltage source and the lamp and having a switching contact connected between a terminal of said DC voltage source and one input terminal of said converter.
 10. A circuit as claimed in claim 9 further comprising a timing device connected across the terminals of said DC voltage source via said switching contact and having a normally closed contact connected in series with a terminal of the DC voltage source and an input terminal of the converter whereby activation of said timing device after a given time period opens said normally closed contact to deenergize the converter. 